The odds of Sega releasing new hardware is slim to nill at this point. It just doesn't make any sense from a business perspective.
Most Japanese game companies tend to heavily focus on the domestic market. Right now, consoles and console games aren't doing very well over there. Gamers are increasingly turning to mobile and online titles.
After Sonic Boom for the Wii U bombed hard last year, Sega announced that they would be moving their resources to focus on those two avenues. As well as their already lucrative gambling (pachinko) properties. If you look at their list of upcoming games, only Yakuza 5 will be coming to console. The game has already been out three years in Japan, and is only now getting world wide localization. It's also going to be a PlayStation 3 exclusive. It will not be coming to current gen systems. That says a lot.
Most big Japanese publishers are doing the same thing. Both Capcom and Konami will be moving away from consoles. Even Nintendo is struggling, and has started releasing games for mobile.
Here in North America, Sega lost a lot of goodwill with gamers for ending the lives of the Saturn and Dreamcast so quickly. They lost a lot of clout in the industry after that, as well as a lot of money. More recent stinkers like Sonic Book and Aliens: Colonial Marines further eroded their reputation. If they did release new hardware, I think it would be looked upon with skepticism.